Apparatus for performing chemical tests



Oct. 30, 1956 r. A. HEwsoN APPARATUS RoR PERFORMING CHEMICAL. TEsTs 3Sheets-Sheet 1 Filed April 23, 1952 l l l /l/l l l l l l l l l l l l l ll l INVENTOR. THOMAS A. HEWSON Fig. l

ATTORNEYS Oct- 30, 1956 i T. A. HEwsoN 2,768,879

APPARATUS PoR PERFORMING CHEMICAL TESTS Filed April 25, 1952 ssheets-sheet 2 02N /loo HEATER INVENToR. 7e THOMAS A. HEwSoN Fig. 6 BVM,2mm/V MMM,

ATTORNEYS Oct. 30, 1956 T, A, HEwsoN f 2,768,879

APPARATUS FOR PERFORMING CHEMICAL TESTS Filed April 25, 195.2 5Sheets-Sheet 3 Fig. 5

l l THOMAS Auping/@lt BVM, '2mm a MMM ATTORNEYS APPARATUS FOR PERFORMINGCHEMICAL TESTS Thomas A. Hewson, Medield, Mass., assignor to Lessellsand Associates, Inc., Boston, Mass., a corporation of MassachusettsApplication April 23, 1952, Serial No. 283,927

6 Claims. (Cl. 23--253) My invention relates to apparatus for performingchemical tests automatically and comprises an improvement upon apparatusof the type disclosed in my prior United States Letters Patent Nos.2,550,067 and 2,560,- 107.

The primary object of my present invention is to facilitate and makemore eiiicient the construction and operation of apparatus forperforming a series of operations on samples of material contained intest-tubes or the like.

Another object of the invention is to provide a relatively small andinexpensive chemical testing machine suitable for use in individualdoctors offices, small processing plants, and the like.

An important feature of the invention resides in a simple, compactmachine incorporating a combination of elements for performing asequence of steps such as adding reagents, heating, cooling, etc., andincluding a receptacle carrier suspended from a central column above aheater and fluid container and beneath a reagent dispenser, themovements of the carrier and dispenser being controlled by mechanismhoused in the central column. The operating mechanism is thus securelyprotected from dirt and fluids, while the external elements areconveniently exposed for easy cleaning and observation.

These and other objects and features of the invention will be morereadily understood and appreciated from the following detaileddescription of a preferred embodiment selected for purposes ofillustration and shown in the accompanying drawings, in which:

Fig. l is a View iu vertical cross-section through a machine constructedin accordance with one embodiment of the invention,

Fig. 2 is a View in cross-section taken along the line 2-2 of Fig. 1,

Fig. 3 is a View in cross-section taken along the line 3 3 of Fig. l,

Fig. 4 is a View in cross-section as in Fig. 3 showing the relation ofthe elements at the end of the first motion of the carrier,

Fig. 5 is a View in cross-section as in Fig. 3, showing the relation ofthe elements at the completion of the cycle of the machine, and

Fig. 6 is a circuit diagram showing the control circuit for the machine.

The machine of my invention, as shown in the embodiment illustrated inthe drawings, is organized about a heavy cylindrical casting forming abase 10 adjacent the upper surface of which is welded, or otherwiserigidly secured, an annular platform 12 serving as a base support for anupright cylindrical tube or column 14 mounted coaxially with the mainbase casting 10. Rigidly secured to the lower surface of the annularplatform 12 is a pair of depending spacer bars 16 to which a metalmounting plate 18 is secured. A small motor 20 having an integral gearreduction system 22 is bolted to the lower surface of the mounting plate1-3 and is provided with an upright shaft 24 which revolves at the rateof one turn in each ten mintes when the motor is supplied withalternating current arent f' ice at about volts and 60 cycles. The motorshaft 24- is received in a cylindrical coupling block 26 and securedagainst relative rotation therewith by means of a transverse pin 28provided with rounded protruding heads 84 at each end.

Also received in the coupling block 26 is the lower end of the maindrive shaft 30, extending vertically upward tlirough the tubular column14 and fixed in the block 26 by means of a set screw 32. At the top ofthe column 14 there is lixedly mounted a block 36 in which is secured abearing 38 for an intermediate portion of the vertical shaft 30. In thetop of the block 36 there is cut a broad transverse slot 40 in whichslides a latch or slide member 42, best shown in Figs. 3, 4 and 5, andprovided in turn with an ovoid center slot accommodating the lowerportion of an eccentric 44 secured to the shaft 30. As the shaft 30turns, the eccentric 44 turns with it and moves the latch 42 back andforth in the slot 40 in the top of the block 36.

The eccentric has an upper portion 46 upon 'the oifset portion of whichis secured one end of a torsion spring 70. A set screw 4S also passesthrough the upper portion of the eccentric and serves to lock the latterupon the shaft 30. Resting upon the upper surface of the eccentric is abushing 54 which in turn supports a circular plate 56 mounted for freerotation upon the bushing 54 and providing support for a depending skirtor iiange 62 extending downwardly to a plane just above the level of thetop of the tubular column 14.

A circular dispensing plate 58 is integral with a knob 6i? and securedto the upper end of the shaft 3@ by means of a set screw 5?. The plate58 is provided with two sets of spaced, thrcugh-and-through holes, shownin Fig. 2 at 1, 2, 3 and 1, 2 and 3. Corresponding holes in each set arelocated degrees apart. Cut in the plate 56 are a pair of opposeddischarge orifices or chutes 61 and 61', arranged to underlie the holesin the dispensing plate 5S as the two plates are rotated relative toeach other. A unitary carrier plate 64 is secured to the skirt 62 andcomprises essentially two opposed arm portions integral with a centerhub. At the outer end of each arm of the carrier plate 64 there isdisposed a test-tube holder 66 pivoted to the carrier as shown at 68.

The rotation of the shaft :ttl at the rate of one revolution per tenminutes causes similar rotation of the dispenser plate 58. Tabletsplaced in the holes 1, 2, 3 or 1', 2 and 3 will be discharged throughthe chutes 61 or 61 and thence into a test-tube held in the appropriateone of the holders 66. But beneath the carrier 64 on one side of theplatform 12 there is a semi-circular can or container 74 in which ismounted an electrical resistance heater 76, while on the other side ofthe platform there is mounted a similar can 72 in which a coolant liquidmay be placed. In performing tests, such as the Wilkerson-Heftmann testfor the sugar content of human blood, it is required that the blood beheated while three reagent tablets are introduced, the heat beingreduced shortly after the introduction of the second tablet and thendrastically reduced after the introduction of the third reagent tablet.Consequently the carrier -is driven, by means now to be escribed, from aposition in which the test tube 69 is directly opposite the heater 76 toa position slightly spaced from the heater and finally to a position inwhich its lower end dips into coolant liquid in the container 72.

As the shaft 30 turns the eccentric 46 it moves the lower end of thetorsion spring 70 in counterclockwise direction thus exerting torque onthe plate S6. However, the skirt 62 carries an inwardly projecting stop50 having a notch or step 52 and disposed in line with the sliding latchmember 42. The latch engages the stop 50 land holds the skirt 62, theplate 56 and the carrier 64 against rotation until such time as theeccentric 44 acts to slide the latch inwardly so that the stop` 50 ridesup on the notch 52. Then the carrier moves a distance proportional tothe length of the notch7 and the carrier then comes to rest again `asthe notch 52 engages the latch 42. This short movement is effective toremove the test tube 69 from close proximity to the heater 76. Finallythe eccentric 44 acts to disengage the latch 42 from the stop Sti, andthe spring 7 t) then acts to turn the plate 56, skirt 62, and carrier 64through an angle of approximately 165 degrees, or until the stop StBcomes into engagement with the opposite corner of the latch 42. Duringthis movement the test-tube 69 rides over the end of the container '74,over the end of the container 72 and then returns to vertical positionwith its lower end below the level of the cooling liquid in the lattercontainer.

The cycle of operation of the apparatus can best be :appreciated from acomparison of Figs. 3, 4 land 5. In Fig. 3 the elements 4are shown inposition as the cycle starts. Hole l is just to the right of the chute61 and the latch 42 is fully engaged with the stop Si). The eccentric 44Vis in position forcing the latch to its extreme right hand position.Although not shown in the figure the test tube 69 is now close to theheater '76.

In Fig. 4 it will be seen that the plate 53 has been rotated through 90degrees (2.5 minutes), during which movement the tablet from hole ll hasbeen discharged into the tube 69. Also, however, the latch 42 has beenmoved to the left by the 90 degree rotation of the eccentric 44 and haspermitted the skirt 62 and stop 50 to move va few degreescounterclocliwisa as shown by the arrow, to move the test tube away fromthe heater 76. r[he hole 2 has previously registered with the chute 61tand discharged the second tablet into the tube 69.

In Fig. 5 the full ten minute cycle has been completed. The dispenserplate 53 has rotated 180 degrees, discharging the second and thirdtablets into the tube 69. However, the eccentric 44 has now moved thelatch 42 to its extreme left hand position, freeing the stop 50 andpermitting the spring 70 to rotate the carrier 64 and tube 69 about 165degrees, until the latch engages the stop once more but upon the cornerdiametrically opposite to that formerly engaging the stop 50.Consequently the tube 69 is 180 degrees opposite its starting position.Of course the holes 2 and 3 are so spaced upon the plate 56 that thethird tablet is discharged just before the latch is disengaged. For thesake of clarity the holes 1', 2 and 3 have been omitted from Figs. 3, 4and 5.

To provide control means for the mechanism just described there isprovided in the base of the machine a pair of switches and a pilotlight, wired as shown in the circuit diagram of Fig. 6. From one side ofa supply line la lead ltr@ runs to a pilot light dit, the motor 20, andthe heater 76. The other terminals of the motor and heater are connectedby a line 102 to a two position switch 8S operated by the cam heads 84on the ends of the pin 2S in the coupling block 25. When the elementsare in the positions shown in Fig. 6, the circuit is open, since theonly return path is through a lead 194 running through a spring pushbutton switch Se to the other side of the supply line, and the latterswitch is normally open. When the switch 86 is closed manually, themotor 26 and heater 76 are energized, vas well as the pilot light. Whenthe motor has turned the appropriate cam head d4 to release the switchS3, the pilot light is disconnected from the circuit, and the normaloperating circuit established through a lead 106 from the supply line tothe second contact member of the switch S3.

In o erating the apparatus herein described, the operator first removesa cylindrical casing '73 which tits over the apparatus, thereby exposingthe interior of the machine. The necessary reagent tablets are placed inthe appropriate holes in the plate 58, the can 72 tlled with cold wateror other liquid, the test tube placed in the receiver, and the switch 86manually closed. The pilot light immediately comes on, if the machine isproperly synchronized; if not, the light will not come on until the camhead S4 operates the switch 83. When the pilot light goes out, it is anindication that the regular Aoperating circuit is established and thecycle begun. At the end of the cycle, the other of the cam heads againlights the pilot light through the switch S8 and disconnects the `motorand heater. The second lighting of the pilot light is an indication thatthe cycle has been completed and the tube ready for removal andobservation. It also indicates that the machine is ready to undertakeanother cycle. The second test tube will then be in position to startthrough the cycle, and Iit is `only necessary to place the reagenttablets in the proper holes in the plate 58, depress the switch 36 untilthe light goes out, and wait until the light comes on once more toindicate the end of another cycle.

Those skilled in the art will readily understand and appreciate that theembodiment 'herein described and illustrated is but exemplary of manypossible variations. The number and timing of the dispensing operationsdepends upon the number and angular position of the hole-s in the plate55. Other plates may be provided for perform-ing various tests.Moreover, by varying the number of notches in the stop Sti it ispossible to introduce several step movements of the carrier and testtubes. The distance the latch 42 must move in each notch determines thetime before a movement of the carrier, while the length of each step ornotch in the stop 5d determines the `angular rotation effected by thecarrier. Moreover the number of stops may be increased to any desirednumber to bring about an almost infinite variation in the timing andextent of the movements of the carrier. The cans or containers 72 and'74 may be varied also to provide any desired succession of heating andcooling steps or alternations of heating and cooling.

It is especially to be noted that the electrical control elements areall housed securely beneath the platform #and mounting plate in the basewhere they cannot be damaged by liquids, reagent powders and the like.Similarly the mechanical trains are concealed and protected by thetubular column 14 and the skirt 62. The exposed portions mayconveniently be made from stainless `steel and are shaped and arrangedto facilitate easy cleaning and inspection.

`Perhaps the most important advantage offered by the apparatus of myinvention is the fact that it provides completely automatic andextremely simple means by which totally unskilled personnel canaccomplish complex chemical testing procedures.

Having thus disclosed my invention, what l claim as new and desire tosecure by Letters Patent of the United States is;

l. Apparatus ofthe class described, comprising a base, a vertical shaftmounted on said base, means for turning said shaft, a perforated platesecured to said shaft, a receptacle carrier freely mounted on said shaftbeneath said plate, a spring mechanically connected to said shaft andsaid carrier, a xed support, a latch mounted on said support andnormally preventing movement of said carrier, and means actuated by saidlshaft to disengage said latch and permit said spring to rotate saidcarrier, whereby said shaft turns said plate at a substantially constantrate while said carrier remains at rest until turned by said spring.

2. Apparatus of the class described, comprising a base, a shaft mountedvertically upon said 1oase, means for driving said shaft at asubstantially constant rate, a perforated plate mounted at the upper endof said shaft, a tubu lar column mounted on said base and surroundingthe lower portion of said shaft, a carrier supported upon said columnfor rotation about said shaft, a receptacle receiver secured to saidcarrier, a torsion spring connected mechanically to said shaft and saidcarrier, a stop member secured to saidcarrier, and a latch actuated byrotation of the shaft and normally engaging said stop to hold saidcarrier against rotation, disengagement of the latch and stop causingsaid spring -to rotate the carrier.

3. Apparatus of Ithe class described comprising a cylindrical base, acentrally located `tubular column secured to said base, an arcuateheater-containing compartment and an arcuate luid container resting onsaid base in nesting relation with said column, a receptacle carriermounted on said column for rotation above said compartment andcontainer, a tablet d-ispenser coaxial with said column and disposedabove said carrier, a shaft disposed Within said co-lumn and secured tosaid dispenser, rreans for turning said shaft at a substantiallyconstant rate, and latch-controlled means actuated by the shaftincluding a torsion spring connected to the carrier and the shaft forcausing intermittent rotation of the carrier.

4. Apparatus of the class described, comprising a vcrtically disposedshaft, a reagent dispenser fixed to the upper end of the shaft, areceptacle carrier mounted for rotation beneath said plate upon an axisconcentric with said shaft, a spring coupling the carrier to the shaft,cam controlled mechanism operated by the shaft for alternately lockingand unlocking the carrier against rotation, and means for turning theshaft at a constant rate.

5. Apparatus of the class described comprising a vertically disposedshaft, a reagent dispenser fixed to the upper end of the shaft, areceptacle carrier mounted for rotation beneath said plate upon an axisconcentric with 6 said shaft, a spring coupling the carrier to theshaft, a cam fixed to said shaft, a sliding latch controlled by saidcam, a stop fixed to said carrier in position to engage said latch, saidcam being effective to move the latch in and out of engagement with thestop, and means for turning the shaft.

6. Apparatus of the class described comprising a vertically disposedshaft, a reagent dispenser fixed to the upper end of the shaft, areceptacle carrier mounted for rotation beneath said plate upon an axisconcentric with said shaft, a spring coupling the carrier to the shaft,a cam fixed to said shaft, a sliding latch, a stop fixed to said carrierin position to engage said latch at two positions apart, said cam beingeffective to move the latch from one position to the other, and meansfor turning the shaft.

References Cited in the file of this patent UNITED STATES PATENTS1,054,939 Platt Mar. 4, 1913 2,111,529 Dalton Mar. 15, 1938 2,198,137Suppiger Apr. 23, 1940 2,550,067 Hewson Apr. 24, 1951 2,560,107 HewsonJuly 10, 1951 2,653,083 Wanzer Sept. 22, 1953

2. APPARATUS OF THE CLASS DESCRIBED, COMPRISING A BASE, A SHAFT MOUNTEDVERTICALLY UPON SAID BASE, MEANS FOR DRIVING SAID SHAFT AT ASUBSTANTIALLY CONSTANT RATE, A PERFORATED PLATE MOUNTED AT THE UPPER ENDOF SAID SHAFT, A TUBULAR COLUMN MOUNTED ON SAID BASE AND SURROUNDING THELOWER PORTION OF SAID SHAFT, A CARRIER SUPPORTED UPON SAID COLUMN FORROTATION ABOUT SAID SHAFT, A RECEPTACLE RECEIVER SECURED TO SAIDCARRIER, A TORSION SPRING CONNECTED MECHANICALLY TO SAID SHAFT AND SAIDCARRIER, A STOP MEMBER SECURED TO SAID CARRIER, AND A LATCH ACTUATED BYROTATION OF THE SHAFT AND NORMALLY ENGAGING SAID STOP TO HOLD SAIDCARRIER AGAINST ROTATION, DISENGAGEMENT OF THE LATCH AND STOP CAUSINGSAID SPRING TO ROTATE THE CARRIER.